Will this fit my tailgate or bumper mount location?

This unit is designed as a 3rd brake light replacement for your center high-mounted position. Verify the mounting footprint and connector type against your OEM light before ordering.

Do I need to reprogram anything for the dual function to work?

No reprogramming needed. The cargo lamp and brake functions operate on their existing factory circuits — it's a drop-in replacement.

What about weatherproofing — is this sealed against water?

It's a complete sealed light assembly. Make sure the connector stays dry and clear of road debris where it plugs into the vehicle harness.